mineral

Blue calcite

Calcite (CaCO₃), likely blue calcite with minor matrix minerals

AI-generated identification · may be incorrect

Pale blue, translucent to opaque, with vitreous-to-pearly luster and prominent rhombohedral cleavage; Mohs hardness 3, making it easily scratched by a knife. Calcite is trigonal and commonly effervesces strongly with dilute hydrochloric acid.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms when calcium-rich groundwater or hydrothermal fluids precipitate carbonate, often in cavities and veins; the blue color commonly results from inclusions or trace elements. The specimen’s exact geological age cannot be determined visually.

Uses & applications

Used mainly as a collector specimen and ornamental stone; calcite is also important industrially in cement, lime, aggregate, soil treatment, and glass manufacture.

Geological facts

Calcite shows strong birefringence: transparent pieces can visibly double printed lines. Blue calcite is often confused with celestite, fluorite, or blue aragonite.

Field identification & locations

Look for rhombohedral cleavage, low hardness, and acid reaction; a streak test is white. Common sources include Mexico, Madagascar, Brazil, the United States, and Pakistan.